Field of the Invention
Embodiments of the invention relate to vortex tubes. More specifically, embodiments of the invention relate to vortex tubes having an arcuate hot leg.
Background
The vortex tube was invented in 1933 by French physicist George Ranque and improved in 1947 by Rudolph Hilsch. Thus, vortex tubes are also known as the Ranque-Hilsch vortex tube. In general, a vortex tube is a mechanical device that separates compressed fluid into hot and cold air streams. It has no moving parts, and does not rely on electricity or chlorofluorocarbons etc. to achieve the temperature separation. Vortex tubes are commonly used in spot cooling applications.
Fluid that rotates about an axis in a cyclonic effect is called a vortex. A vortex tube creates a vortex from compressed air and separates it into two air streams, one hot and one cold. The compressed air is injected into a cylinder perpendicular to the longitudinal axis. The cylinder (also referred to as a vortex chamber) is proportionally larger in diameter than either the hot leg (which is the long leg) or the cold leg (the short leg) and both legs are generally coaxial and collinear with the vortex chamber.
The injection of air into the vortex chamber causes it to rotate at high speed. When the rotating air is forced down the inner walls of the hot leg at the distal end a small portion of the air exits through a valve as the hot air stream. The remaining air is forced back through the center of the incoming stream at a slower speed. The heat in the slow moving air is transferred to the faster moving air traveling down the outer portions of the tube thus resulting in a cool airstream which passes back through the center of the vortex chamber and out the cold leg through a cold air exhaust port. In general, the longer (up to about 0.5 meters) the hot leg the greater the temperature separation, that is the difference in temperature between the hot stream and the cold stream. Unfortunately, in many applications, the such long legs would make the use of the vortex tube impractical. As a result, many commercial vortex tubes have relatively short hot legs and suffer from reduced cooling capabilities.